System and method for converting organic waste into methane and other useful products

ABSTRACT

An organic waste processing system and method for producing a slurry for the production of bio-gas, transportation fuels and chemical products, and a residual sad. The system includes (i) a hopper configured to receive sorted organic waste having contaminants from one or more sources, (ii) a separator system in communication with the hopper and configured to receive the sorted organic waste from the hopper and to remove at least a portion of the contaminants in the sorted organic waste, (iii) a complimentary liquid tank in communication with the separator system and containing complimentary liquids, (iv) a wash water liquid tank in communication with the separator system and containing wash water, (v) a product tank in communication with the separator system and configured to receive the sorted organic waste from the separator system, (vi) a make-up product tank in communication with the separator system and configured to receive the sorted organic waste from the separator system having low COD, (vii) a anaerobic digester system configured to receive the sorted organic waste from the product tank, and (viii) a programmable logic controller.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention is generally related to the processing ofmunicipal solid waste, and more particularly to a system and method forconverting organic waste into methane for energy production or theproduction of other useful transportation fuel and chemical products.

2. Discussion of the Background

Waste disposal is an issue faced by nations across the world. In recenthistory, waste has primarily been disposed of in landfills, whichrequire substantial land, engineering and environmental monitoring andmanagement resources. Regulatory and political bodies, as well asgenerators of waste, are increasingly interested in reducing wastevolumes, diverting wastes from landfills and incinerators whilepromoting the more sustainable use of waste products. It is thereforedesirable to develop technologies that not only reduce the amount oflandfilled and incinerated waste, but also to capture and use suchmaterial for beneficial purposes.

Recently, recycling and composting of residential and commercial wastematerials has become a preferred way to reduce the amount of wastematerials that would otherwise be directed to landfills. Although thereis some variation among geographic regions, it has become common torecycle paper, metals, glass and plastic materials. More recently,organic materials such as green waste (e.g., tree and grass clippings)and food waste are being commercially composted for use as a soilamendment or occasionally utilized for the generation of methane gas.However, current compost practices produce products of limitedcommercial value, and the known techniques utilizing organic materialsfrom a municipal waste stream in an anaerobic digestion process havefailed to achieve consistent, high levels of methane production.

Thus, there currently exist deficiencies associated with wasteprocessing, and, in particular, with organic waste processing.

SUMMARY OF THE INVENTION

Accordingly, one aspect of the present invention is to provide anorganic waste processing system to produce a slurry for the productionof bio-gas, transportation fuels and chemical products, and a residualsolid. The system includes (i) a hopper configured to receive sortedorganic waste having contaminants from one or more sources, (ii) aseparator system in communication with the hopper and configured toreceive the sorted organic waste from the hopper and to remove at leasta portion of the contaminants in the sorted organic waste, (iii) acomplimentary liquid tank in communication with the separator system andcontaining complimentary liquids, (iv) a wash water liquid tank incommunication with the separator system and containing wash water, (v) aproduct tank in communication with the separator system and configuredto receive the sorted organic waste from the separator system, a make-upproduct tank in communication with the separator system and configuredto receive the sorted organic waste from the separator system having lowCOD, (vii) a anaerobic digestor system configured to receive the sortedorganic waste from the product tank, and (viii) a programmable logiccontroller. The separator system includes a primary centrifugalseparator. At least a portion of the complimentary liquids from thecomplimentary liquid tank is periodically injected into the separatorsystem upon request. At least a portion of the wash water from the washwater tank is periodically injected into the separator system uponrequest. At least a portion of the organic waste from the make-upproduct tank is periodically injected into the product tank uponrequest. The anaerobic digestor system includes a flow meter, a controlvalve and an anaerobic digestor tank. The control valve has an open andclose position. The programmable logic controller is configured toperiodically inject organic waste into the anaerobic digestor tank toenhance anaerobic digestion. The programmable logic controller isconfigured to monitor the flow meter and to open and close the controlvalve to inject the organic waste into the anaerobic digestor tank.

Another aspect of the present invention is to provide a method forproducing a slurry for the production of bio-gas, transportation fuelsand chemical products, and a residual solid. The method includes (i)receiving, into a hopper, sorted organic waste having contaminants fromone or more sources, (ii) receiving, into a separator system incommunication with the hopper, at least a portion of the sorted organicwaste from the hopper and removing at least a portion of thecontaminants in the sorted organic waste, (iii) periodically injecting,from a complimentary liquid tank having complimentary liquid, at least aportion of the complimentary liquids into the separator system uponrequest, (iv) periodically injecting, from a wash water liquid tankhaving wash water, at least a portion of the wash water into theseparator system upon request, (v) receiving, into a product tank incommunication with the separator system, at least a portion of thesorted organic waste from the separator system, (vi) receiving, into amake-up product tank in communication with the separator system, atleast a portion of the sorted organic waste from the separator system,(vii) periodically injecting, into the product tank, at least a portionof the organic waste from the make-up product tank upon request, (viii)receiving, into a anaerobic digestor system, the sorted organic wastefrom the product tank, (ix) anaerobic digesting the organic waste in theanaerobic digestor tank, (x) controlling the flow of the organic wasteinto the anaerobic digestor tank to enhance anaerobic digestion. Theseparator system includes a. (primary centrifugal separator. The make-upproduct tank receives organic waste having a low COD. The anaerobicdigestor system includes a flow meter,a control valve and an anaerobicdigestor tank, wherein the control valve has an open and close position.The flow is controlled by a programmable logic controller that isconfigured to periodically inject organic waste into the anaerobicdigestor tank. The programmable logic controller is configured tomonitor the flow meter and to open and close the control valve to injectthe organic waste into the anaerobic digestor tank.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the present invention and many of theattendant advantages thereof will be readily obtained as the samebecomes better understood by reference to the following detaileddescription when considered in conjunction with the accompanyingdrawings, wherein:

FIGS. 1-4 are block diagrams illustrating organic waste processing inaccordance with an embodiment of the present invention;

FIG. 5A is a flow chart illustrating organic waste processing inaccordance with an embodiment of the present invention;

FIG. 5B is a flow chart illustrating FOG processing in accordance withan embodiment of the present invention;

FIG. 5C is a flow chart illustrating anaerobic digester fuel productprocessing in accordance with an embodiment of the present invention;and

FIG. 6 is an exemplary organic waste processing apparatus in accordancewith an embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the drawings, wherein like reference numerals designateidentical or corresponding parts throughout the several views, preferredembodiments of the present invention are described.

The present invention provides a system and method for convertingorganic waste materials into a uniform fuel product, also referred toherein as feedstock, that is suitable for anaerobic digestion to producebio-gas, transportation fuels and/or chemical products and a residualsolid.

There are four general stages in the anaerobic methanogenesis process:hydrolysis, acidogenesis, acetogenesis, and methanogenisis. Organicwaste is typically delivered to the waste processing facility in theinitial stages of hydrolysis. Once processing begins, organic wastemoves from the hydrolysis stage to the acidogenesis stage. The pH levelgoes from approximately 5.0 to approximately 4.0 during the first day.Continued aeration and recirculation brings the material to a pH of lessthan approximately 3.7. The organic waste is in the acidogenesis stageonce the pH level is approximately 3.6. This typically takesapproximately three to four days after the initial processing step.During this initial three day period, the COD moves from approximately<200 g/L to <160 g/L. Essentially, the available organics are beingdigested.

After approximately 2 to 3 days, the organic waste takes on a vinegarlike smell. At this point the organic waste is liquid enough to be usedas wash water again. Using the organic waste as wash water increases thefuel product's pH and the COD. However, after approximately 24 to 48hours the product returns to the acidogenesis phase and the pH and CODdecrease significantly. Generally, the longer the product stays in thetank or in the digester feed station the less gas the product willproduce.

According to at least one embodiment, a processing facility receivesorganic waste that is source separated, meaning it has been separatedfrom general solid waste. Such organic materials may be collected fromcommercial and/or consumer sources, such as grocery stores, hotels,restaurants, schools, food processing facilities, residential homes, andthe like.

Organic waste materials may contain contaminates which must be screenedand otherwise separated. Such non-digestible contaminates include,without limitation, plastic, glass, ceramics, bones, seeds, cardboard,and the like. Through the use of one or more centrifugal separators aswell as sorting and screening, source separated organic materials areslurried and cleaned of these non-digestible contaminates. According toat least one embodiment, a “Primary Separator” and a “SecondarySeparator” are utilized. The resulting slurried organic waste is auniform fuel product that is suitable for use in the anaerobic digestionprocess to produce bio-gas and a residual solid.

Liquids with organic strength may be added during the contaminateremoval process for use as a screen wash water. Liquids with organicstrength may also be added during the anaerobic digestion process tocompliment the fuels benefits in the anaerobic digester. Liquids withorganic strength can be obtained by separating such material from itscontainer, such as milk from a container, or receiving them in bulktankers. According to at least one embodiment, the organic liquids arestored in holding tanks prior to use in a centrifugal separator oranaerobic digester.

Ideally, although not required, the cost associated with the processing,transport and ultimate disposal of the organic waste materials pursuantto the present invention should be equal to or less than the cost fortraditional waste disposal, such that the cost is at least neutral tothe customer. The source separation and collection program should alsobe easy for the customer to implement. The energy benefits of theorganic waste material, such as, without limitation, renewable,electricity revenues, transportation fuel revenues, beneficial chemicalproducts revenue, and gas commodity revenues, are captured.

Using the present invention, it is possible to (1) produce consistent,high quality feedstock that can be safely added to an anaerobicdigestion process, or fuel/chemical process and which will increasemethane gas production. Transportation fuels, other beneficialchemicals, and (b) maximize diversion of organic waste from landfills.

An important consideration in the anaerobic digestion process is thecontrolled addition of feedstock to minimize stress on the biologicprocess. In the case of municipal bio-solids digesters, significantstress on the biology in the digester may cause a complete breakdown ofthe process, requiring the unit being taken off line and cleaned out.Therefore, waste processing facilities are often cautious aboutintroducing material other than bio-solids to their digesters.

Although food waste has been shown to benefit methane gas production inan anaerobic digestion process, its use has been limited due tocontamination (e.g., tableware and packaging) and inconsistent organicproperties. It is therefore important to separate contaminants from theorganic waste, and create a fuel with consistent chemical properties.

I. Organic Waste Categorization System

Methane gas production from an anaerobic digester is improved by theaddition of materials with high amounts of chemical oxygen demand (COD).The addition of food waste, which typically has a COD higher thanNo-solids, to the anaerobic digestion process increases methane gasproduction. However, not all food waste has the same COD. For instance,fats, oils, and greases (FOG) typically have a very high COD. Food wastewith low FOG content typically has a low COD.

High-FOG food waste generally originates from post-consumer entities,such as restaurants. Low-FOG food waste generally originates frompre-consumer entities, such as grocery stores and food processingfacilities. However, grocery stores with Deli's may also have high-FOGfood waste.

According to at least one embodiment, the organic waste is classifiedinto one of three categories based on its collection point: (i)pre-consumer materials (PrC), (ii) post-consumer high FOG (PCHF), and(iii) post-consumer low FOG (PCLF). Obviously, additional categories arepossible to provide greater precision in food waste recipes within thescope of the present invention. For example, other possible“complimentary liquids” include grease trap material, decased consumerproducts, off-spec consumer products, and beverage industry industrialprocess waste waters.

II. Multi-Tank Food Waste Blending System

The present invention utilizes a multi-tank system which allows for theacceptance, processing and beneficial use of a very high percentage oforganic waste. The multi-tank system of the present invention produces aconsistent fuel product and reduces the amount of landfilled waste.According to at least one embodiment, four or more twelve-thousandgallon storage tanks are utilized, including, without limitation, (i) afinal product tank (Tank 1), (ii) a make-up product tank (Tank 2), (iii)a wash water tank (Tank 3), and (iv) a complimentary liquids tank (Tank4). Optionally, in addition to the four above-identified tanks, twoadditional twelve-thousand gallon storage tanks arc utilized, including,without limitation, (v) a raw FOG liquids tank (Tank 5), and (vi) aphase separated FOG liquids tank (Tank 6). All of the storage tanks aredesigned for recirculation. A compressed air line on the fill side ofeach tank induces air during the recirculation process. The tanks areset on a reinforced concrete slab for use as a foundation. Liquids areperiodically added to the organic waste to clean screens in thecentrifugal separators and make the product capable of being pumped.

Tank 1

Tank 1 contains food waste slurry suitable for use as anaerobicdigestion feedstock. Based on current findings by the inventors of thepresent invention, according to at least one embodiment. Tank 1 shouldcontain organic waste slurry having substantially (i) ten to fifteenpercent in total solids, and (ii) high levels of chemical oxygen demand(COD). The content of Tank 1 is blended from (i) material processed fromthe Primary Separator and/or Secondary Separator, (ii) Tank 2, (iii)Tank 5 and/or (iv) Tank 6. According to one embodiment, Tank 1 is neveremptied out. Instead, organic waste is continually blended in from theabove-identified sources. According to at least one embodiment, beforethe organic waste is removed from Tank 1 for anaerobic digestion use, itis tested, without limitation, for (i) total solids, (ii) volatilesolids, (iii) raw fats, oils, and greases (FOG), (iv) pH, (v) dissolvedoxygen, (vi) conductivity, (vii) chemical oxygen demand, (viii) totalorganic carbon, and (ix) total Kjeldahl nitrogen.

Tank 2

Tank 2 contains slurry not yet suitable for use as anaerobic digestionfeedstock. The content of Tank 2 is from the Primary Separator and/orSecondary Separator. The content of Tank 2 is blended into Tank 1 asneeded.

Tank 3

Tank 3 contains liquid not yet suitable for anaerobic digestion use, butwhich can be injected into the Primary Separator and/or SecondarySeparator as wash water to thin the organic waste slurry and clean thescreen, or Tank 1 as an organic waste slurry thinner. The content ofTank 3 is from the Primary Separator, Secondary Separator and/or sumps.

Tank 4

Tank 4 contains liquid not yet suitable for anaerobic digestion use, butwhich can be injected into the Primary Separator and/or SecondarySeparator as wash water and/or blended with materials to create asuitable anaerobic digestion feedstock. The content of Tank 4 is fromthe Primary Separator, Secondary Separator and/or inbound tanker trucks.

Tank 5

Tank 5 contains cleaned FOG that has been generally be cleaned of solidsin the Secondary Separator. Once stored in tank 5, the FOG is then sentto the FOG Phase-Separation System. The content of Tank 5 is also usedfor wash water in both the primary and secondary separators.

Tank 6

Tank 6 accepts FOG processed by a FOG Phase-separation system (“FOGSeparation System”). A FOG Separation System processes FOG liquids thathave been processed through the Secondary Separator. The purpose of FOGSeparation System is to separate FOG from water. The clarified water,once separated, is discharged to the sanitary sewer or sent to tank 3for use as wash water, and the FOG is directed to Tank 6. The content ofTank 6 is injected into Tank 1 as necessary to increase the chemicaloxygen demand (COD) of the feedstock product.

By means of the present invention, virtually any type of organic waste,including undesirable (low COD) material, may be processed. Rather thanlandfilling or composting (which is less efficient than anaerobicdigestion and other chemical processes with respect to energy creation),undesirable material may be stored and gradually blended-in with organicwaste having a higher COD using the multi-tank arrangement of thepresent invention to create a uniform fuel product. Not only does lessmaterial get landfilled, but the environmental impacts and costsinvolved with transporting waste material to another facility forsubsequent disposal or composting are avoided.

Further, a consistently high quality organic waste fuel product, or“feedstock,” is produced that digester facilities are seeking. Havingmultiple tanks allows a waste processing facility to control recipes offuel product such that there are no significant fluctuations in contentbased on the organic waste that is delivered to, and processed by, thewaste processing facility. The present invention allows for consistentproduction of both solids and COD levels in the final blended fuelproduct.

III. Organic Waste Processing Considerations

There are several factors that should be considered in the processing oforganic waste. The organic waste may be very odiferous and should beprocessed quickly to manage the odors. In fact, such odor management isoften required by waste processing facility permits. Ideally, althoughnot limiting, all equipment contacted by the organic waste is sanitizedor cleaned with hot water at least once per shift to mitigate odors. Tipfloors and equipment require more frequent sanitization depending on thedegree of odor. This sanitizing may be accomplished by several means:(i) a hose system that is configured and sized to accommodate enoughquantity of heated water of an appropriate volume and temperature towash down the tipping floor and equipment; and/or (ii) a power washer,such as a Hotsy hot water power washer, may also be used for sanitizingthe system.

In order to maintain cleanliness and to reduce odors, according to atleast one embodiment, the tipping area is configured to be small suchthat the facility is required to process the organic waste materialquickly to keep it from being stored on the tipping floor area

The feeder unit is configured for easy loading and to tip over for easycleanout if the feeder screws jam. According to at least one embodiment,the tipping area has four-foot walls with a one foot sloped floor fordrainage. Contaminants from the centrifugal separator systems areexpelled at the top and onto a conveyor that deposits the waste in aroll away to a trash container. The waste volume depends on thecontamination levels of the incoming material, but if contaminationlevels are reduced to less than five percent by weight, then the wastevolume is minimal. When the waste container becomes full, it isexchanged with an empty container. Contents of the full waste containerare rolled away for disposal or recycling.

When a tank is filled with processed organic fuel or other materials,the air within the tank is displaced. According to at least oneembodiment, all displaced air is run through a bio filter made with athirty-yard roll off box filled with wood chips to mitigate odors whenfilling tanks. Bio-aire bio-filter supports were installed in the bottomof the thirty-yard roll off box as a plenum.

According to at least one embodiment, a four zone NOM odor mistingsystem is installed so that the odorant can be applied incrementally toreduce odor. Zone 1 covers the tip floor. Zone 2 covers the rest of theinside of the building. Zone 3 covers the building open front area. Zone4 covers the truck load out area.

According to at least one embodiment, the organic waste processingsystem is configured with redundancy. The system can transfer productwith one of multiple transfer pumps. The system is configured to loadtanker trucks, and unload tanker trucks. This may is accomplished bypumping or by other means from any tank to the tanker truck.

According to at least one embodiment, all water used to clean theorganic waste processing facility is captured and either reused as washwater or blended into the fuel product to create a thinner consistency.Complimentary liquids received are stored Tank 4 for later use as washwater or blended into fuel product to achieve the desired recipe.

According to at least one embodiment, unprocessed FOG is accepted andused as both wash water and for COD enhancement in the final product.The FOG material can be subjected to a heat source in Tanks 5 and 6 suchthat the FOG does not congeal.

IV. Control Systems

All fuel processing system functions are controlled by a programmablelogic controller (PLC). The PLC has several control screens that allowfor operation of the processing system in several different modes. Thesystems and equipment can be operated manually or automatically as aresult of a selected process. Automatic operation of the system isaccomplished by accessing a user interface customized for the particulartype of process, including, without limitation, food processing, FOGprocessing, decasing, truck load and unload, and tank recirculation.Manual control of each individual piece of equipment is accessed bymanual screens behind the equipment subgroup page. Alarms are set forvarious conditions requiring user attention.

The PLC includes ladder-style logic program embodied on the touch screenPLC controller. The PLC controls a combination of both remote and localinput and output (IO) modules which in turn control the hardwarecomponents in the system, including, without limitation, starters,variable frequency drives, soft start starters, hydraulic control valvesand the like. The PLC ladder-style control logic program defines thecontrol strategy and the functionality of the system.

A supervisory control and data acquisition (SCADA) interface isconfigured to control of the system remotely over the internet. TheSCADA system allows the use of all the user input and data reportingfunctions of the PLC. The SCADA system can be integrated into the sitesexisting ACADA System allowing control of the system remotely in thesites control room.

According to at least one embodiment, the fuel processing system PLC isconfigured to sense and coordinate valve movements and to start and stopmotors depending on the particular operation the operator has chosen todo. The main process configurations include, without limitation: processfood; process FOG; recirculate tanks; load transfer tanker; and unloadtransfer trailer. Each of the previous screens allow the user to choosewhich pumps to use; choose which tank to fill; choose which tank to usefor wash water. During tank transfer operations the screen allows for;transfer liquids; choose distribution box; choose “from” tank; choose“to” tank,

According to at least one embodiment, both the fuel processing systemand the digester feed system PLC is setup with manual operators for eachvalve to run valve diagnostics. The valves are stainless steel knifegate valves that are hydraulically operated, each with two proximitysensors for position sensing. The control topology includes, withoutlimitation, sensors homerun to the control box and landed on IO strips.Alternatively, distributed IO may be utilized to reduce the number ofcables that need to be homerun to the control box.

The digester feed system controls the feed of the prepared fuel, pumpedfrom Tank 1 at the processing facility to a tanker truck and thentransported to a digester facility, then pumped from the tanker truckinto each digester feed system. To allow for slight inconsistencies inthe fuel product that is fed into the digester, alternatively thecontrol system can be updated with the total solids information of thefuel product delivered to the feed system tank The system calculates thefinal feed rate based on the TS of the fuel and the TS of the digesterprimary and TWAS infeed. This balances the TS load of the digester whichmanages the load transients therefore creating a more stable operatingenvironment.

The digester feed system functions are controlled by a programmablelogic controller (PLC). According to at least one embodiment, the PLChas several control screens that allow for operation of multipledigester feed systems. For each feed system, an operator can input thedesired digester feed rate in gallons per hour. Once the recirculationpump is started via the PLC, and the feed system start is selected, thefeed valve opens and the fuel passes through a flow meter. The flow ismeasured in gallons by the flow meter. Once the desired feed amountsetpoint is reached, the PLC closes the feed valve and waits theremainder of the one hour period for the feed cycle to be restarted.Manual control of each individual piece of equipment is accessed bymanual screens behind the equipment subgroup page. Alarms are set for nofuel feed, pump not started, and various other conditions requiring userattention.

According to at least one embodiment, optionally the digester feedsystem controls the feed of the prepared fuel into each digester using ameasured total solids approach. To allow for consistent feed of the fuelproduct into the digester, the control system is updated hourly with thetotal solids information of the fuel product in the feed system tankfrom the total solids sensing device in the tank. The system calculatesthe final fuel feed rate based on the established total solids feedsetpoint which is based on a setpoint percentage of the feed and thetotal solids feed rate of the digester primary and TWAS infeed. Fuelfeed gallons per hour setpoint may be determined using the followingequation:

RFR=(DSW*S)*FR

RFFG=RFR/FSW

In the above equation, DSW represents the primary & TWAS dry solidsweight, S represents the desired fuel solids percentage, FR representsprimary & TWAS feed rate per hour. RFR represents the required fuelsolids feed rate per hour, FSW represents the weight of fuel solids pergallon, and RFFG represents the required fuel feed gallons per hour.

By programmatically controlling the feed valve, the total solids load ofthe digester is better balanced and the load transients are managedthereby creating a more stable operating environment,

The PLC controlled digester feed system communicates with the wasteprocessing facility's supervisory control and data acquisition system(SCADA). All functions, setpoints, and alarms programmed into the PLCare available to the facilities control room via a SCADA communicationsinterface,

V. Organic Waste Processing

Block diagrams illustrating organic waste processing in accordance withan embodiment of the present invention are shown in FIGS. 1-4. As shownin FIG. 1 commercial and/or consumer generated organic waste iscollected from one or more sources 12 a-12 c via one or more collectionvehicles 14, such as waste trucks or other similar carriers, anddeposited at food processing facility 16. The organic waste may becollected from commercial and/or consumer sources such as grocerystores, hotels, restaurants, schools, food processing facilities,residential homes, and the like. According to at least one embodiment,the food waste is classified into, without limitation, one of threecategories based on its collection point: (i) pre-consumer materials(PrC), (ii) post-consumer high FOG (PCHF), and (iii) post-consumer lowFOG (PCLF). High-FOG food waste typically originates from post-consumerentities, such as restaurants. Low-FOG food waste typically originatesfrom pre-consumer entities, such as grocery stores and food processingfacilities,

The food waste processing facility 16 processes the organic waste intofuel slurry 30, as more detailed in FIG. 2. Reclaimed wash water 18 andorganic liquids 20 are utilized during this processing. Contaminants 22contained with the organic waste are removed and may be furtherprocessed and recovered at a material recovery facility 24. Forinstance, paper and/or plastic 28 may be recovered from the contaminants22. Non-recoverable contaminants 22 are sent to a disposal facility 26.

The fuel slurry 30 may be sent to a compost facility 54 to be used inthe generation of compost 56. Otherwise, the fuel slimy 30 may befurther processed by means of anaerobic digestion 32 to produce carbonmonoxide (CO) 36 and methane 38. Such processing may include cleaningand/or separating any gasses generated by means of the anaerobicdigestion 32. The carbon monoxide (CO) 36 and methane 38 may be convenedto electrical energy 40 to power a plant 42 or electrical utility grid44.

The methane 38 may also be cleaned and compressed 46 and transmitted viaa gas utility pipeline 48. The methane 38 may also be used as LNG/CNGfuel 50 and transported via collection vehicle 52.

As shown in FIG. 2, at the food waste processing facility 16, theorganic waste is unloaded at a tipping area at the waste processingfacility and fed into a hopper, as indicated at blocks 62 and 64. One ormore centrifugal separators may be used to separate non-digestiblecontaminates, as indicated at blocks 66, 68, 70, 72 and 74. According tothe non-limiting embodiment shown in FIG. 2, a primary centrifugalseparator 66 separates non-digestible contaminates 68 from thesemi-processed organic slurry. Such non-digestible contaminates include,without limitation, plastic, glass, ceramics, bones, seeds, cardboard,and the like. Through the use of a centrifugal separator, as well assorting and screening, source separated organic waste is scurried andcleaned of these non-digestible contaminates. The semi-processed organicslurry is then directed to a secondary centrifugal separator 74 whichfurther separates non-digestible contaminates 72 from the semi-processedorganic slurry. Using two or more centrifugal separators allows for agreater reduction in contaminants. For example, and without intending tolimit the present invention, the primary centrifugal separator 66 may beconfigured to remove contaminants greater than 15 millimeters whereasthe secondary centrifugal separator 74 may be configured to removecontaminants greater than 8 millimeters. According to one non-limitingembodiment, the semi-processed organic slurry is directed to a secondarycentrifugal separator 66 by means of one or more pumps, which may beselectable at decision block 70. A portion of the semi-processed organicslurry may be tested, as indicated at block 79.

A determination is made as to which tank the semi-processed organicslurry is directed at decision block 78. The semi-processed organicslurry is then pumped using pumps into an appropriate tank. For example,the semi-processed organic slurry may be pumped to Tank 1 (102), Tank 2(104), Tank 3 (94) and/or Tank 4 (92). Distribution box 1 may be used todirect the semi-processed organic slurry or the final fuel product toone or more of the above tanks or to a truck tanker, as indicated byblocks 106 and 110, and decision block 108. Likewise, distribution box 2may be used to direct the semi-processed organic slurry or the finalfuel product to one or more of the above tanks or to a truck tanker, asindicated by blocks 96 and 98, and decision block 110.

As shown in FIG. 3, complimentary liquids and/or FOG 132 are directedfrom a collection vehicle to gravity screen 134 which separatesnon-digestible contaminates 136. One or more centrifugal separators maybe used to further separate non-digestible contaminates, as indicated atblocks 144 and 146. According to the non-limiting embodiment shown inFIG. 3, a secondary centrifugal separator 144 separates non-digestiblecontaminates 146 from the complimentary liquids and/or FOG. Suchnon-digestible contaminates include, without limitation, plastic, glass,ceramics, bones, seeds, cardboard, and the like. A determination is madeas to which tank the semi-processed complimentary liquids and/or FOG isdirected at decision block 148. The complimentary liquids and/or FOG isthen pumped using pumps into an appropriate tank. For example, thecomplimentary liquids and/or FOG may be directly pumped to Tank 1 (164),Tank 4 (168) and/or Tank 5 (150) from the secondary separator (144). TheFOG may also be pumped to a FOG Phase-separation unit 154 whichseparates the FOG from the clarified water 156. The FOG may then bepumped into Tank 6 at block 160.

The resulting uniform fuel is suitable for anaerobic digestion toproduce bio-gas and a residual solid, k quantity of liquids with organicstrength will be added to the contaminate removal process for use asscreen wash water to increase the benefits of the fuel. A quantity ofliquids with organic strength may also be added to an anaerobic digesterto compliment the fuels benefits in the digester. Liquids with organicstrength can be obtained by separating the liquids from containers orreceiving them in bulk tankers. According to at least one embodiment,the organic liquids are stored in holding tanks prior to use in acentrifugal separator or the anaerobic digester.

As shown in FIG. 4, the fuel slurry 182 may be directed to a fuel slurrystorage tank 186 and/or anaerobic digester 194. According to at leastone embodiment, the fuel slurry 182 is initially pumped into to fuelslurry storage tank 186 by means of pump 184. Flow meter 188 opens andcloses control valve 190 in a controlled manner such that the fuelslurry 182 is periodically pumped via pump 192 into anaerobic digester194.

A flow chart illustrating organic material processing in accordance withan embodiment of the present invention is shown in FIG. 5A. At block202, unprocessed food waste is received at a processing facility. Theorganic waste is identified as belonging to one of the three categoriesdescribed above (PrC, PCHF or PCLF) at block 204.

At blocks 206 and 208, the food waste is then processed by twoseparation systems to remove contaminants and to reduce the volume ofunprocessed food waste into a slurry. According to one non-limitingembodiment, the separation system includes a feeder, a Primary Separator206 and an optional Secondary Separator 208. Unprocessed food waste isinitially dumped into the feeder and then directed to the PrimarySeparator 206 and then to the Secondary Separator 208. The PrimarySeparator 206 uses a vertical rotating set of vanes, screen andcentrifugal force to extract contaminants (e.g., plastic tableware) andto generate a food waste slurry. The Secondary Separator 208 can alsoreceive liquid wastes (e.g., complimentary liquids, grease trap wastes)directly from a grease trap tanker truck off load system. Similar to thePrimary Separator, contaminants are ejected by the Secondary Separator208, captured in a container and either recycled (if a recyclablematerial such a paper or plastic) or disposed of. At blocks 210 and 212,complimentary liquid from tank 4 and/or wash water liquid from Tank 3may be injected into the Primary Separator 206 or the SecondarySeparator 208.

At block 216, semi-processed organic slurry is tested for thepercentages of (i) total solids (TS), (ii) chemical oxygen demand (COD)and (iii) fats, oils, and greases (FOG). The percentage of total solidsis determined using a specially calibrated infrared unit. According toat least one embodiment, a semi-processed organic slurry sample isextracted and weighed. The semi-processed organic slurry sample is thendried to remove the water fraction leaving the solids fraction. Thedifference in weights between the food sample before and after drying isused to determine the percent of total solids.

According to at least one embodiment, the chemical oxygen demand isdetermined using a standard Hach digestion method and a Hach DR5000UV-Vis Spectrophotometer system. The result is a correlation betweenmethod 8000 results, and a Visible Ultraviolet scan at severalwavelengths. The Hach DR5000 UV-Vis Spectrophotometer provides a numberthat correlates generally to a COD number from the Method 8000 digestionnumber.

If the total solids are low then wash water is restricted at block 218.If the COD levels are low then FOG from Tank 6 is injected at block 220.

The semi-processed organic slurry is directed to an appropriate storagetank at block 222. According to at least one embodiment, thesemi-processed organic slurry is directed to the appropriate storagetank using a pumping mechanism. The semi-processed organic slurry isdirected to Tank 1 or Tank 2 depending on the COD levels at block 224.Specifically, if the COD is very low then the semi-processed organicslurry is directed to Tank 2. Otherwise, the semi-processed organicslurry is directed to Tank 1. According to at least one embodiment, thesemi-processed organic slurry is directed to Tank 1 or Tank 2 using apumping mechanism.

At block 228, semi-processed organic slurry is again tested for thepercentages of (i) total solids (TS), (ii) chemical oxygen demand (COD)and (iii) fats, oils, and greases (FOG) using the method describedabove. If the COD is low then FOG from Tank 6 is injected at block 220.

By means of the above, (i) a consistent fuel slurry feedstock isgenerated that, when added to anaerobic digestion systems, willsignificantly enhance methane gas production, and (ii) food waste isdiverted from landfills.

A flow chart illustrating FOG processing in accordance with anembodiment of the present invention is shown in FIG. 5B. At block 242,FOG and/or complimentary liquids are received at a waste processingfacility. The FOG and/or complimentary liquids are directed to a primarygravity screen which separates non-digestible contaminates at block 244.A secondary centrifugal separator (Secondary Separator) separatesnon-digestible contaminates from the complimentary liquids and/or FOG,as indicated at block 246. Such non-digestible contaminates include,without limitation, plastic, glass, ceramics, bones, seeds, cardboard,and the like. At blocks 250 and 248, complimentary liquid from Tank 4and/or wash water liquid from Tank 3 may be injected into the SecondarySeparator.

At block 254, the FOG and/or complimentary liquids are tested for thepercentages of (i) total solids (TS), (ii) chemical oxygen demand (COD)and (iii) fats, oils, and greases (FOG) using the same method describedabove with respect to testing the semi-processed organic slurry.

The complimentary liquids and/or FOG are then pumped out of thesecondary separator using pumps into Tank 5 at block 256. For example,the complimentary liquids and/or FOG may be pumped to Tank 1 (164), Tank4 (168) and/or Tank 5 (150). At block 258, the complimentary liquidsand/or FOG are pumped to a FOG Phase-separation unit which separates theFOG from the clarified water. The clarified water is extracted from thePhase-separation equipment, and then either directed to Tank 3 or to thesewer, as indicated at blocks 260, 262 and 264. The FOG is then bepumped into Tank 6 at block 266.

At block 268, the FOG and/or complimentary liquids are again tested forthe percentages of (i) total solids (IS), (ii) chemical oxygen demand(COD) and (iii) fats, oils, and greases (FOG) using the same methoddescribed above with respect to testing the organic waste. The contentof Tank 6 is injected into Tank I if the COD is low, at block 270.

A flow chart illustrating anaerobic digester fuel product processing inaccordance with an embodiment of the present invention is shown in FIG.5C. The digester feed system functions are controlled by a programmablelogic controller (PLC). The PLC controlled digester feed systemcommunicates with the facility's supervisory control and dataacquisition system (SCADA). All functions, setpoints, and alarmsprogrammed into the PLC are available to the facility's control room viaa SCADA communications interface. For instance, SCADA input and outputis shown at blocks 283, 285, 289, 295, 297, 303, 307, 315, 317 and 319.According to at least one embodiment, the PLC has several controlscreens that allow for operation of multiple digester feed systems. Atblock 282, either a pump cycle start or a pump cycle stop is selected.Depending on the selection, the recirculation pump is either started orstopped, as indicated at blocks 298 and 300. If a pump cycle start wasselected, then a determination is made as to whether the pump actuallystarted, at decision block 302. If the pump did not start, then a pumpalarm is triggered, as indicated at block 306.

At block 282, a feed cycle start, a feed cycle stop or a feed cyclereset is selected. Depending on the selection, the feed cycle is eitherstarted or stopped, as indicated at blocks 286 and 316. If the feedcycle start was selected, an internal one hour feed cycle time is alsostarted at block 308, and the solenoid is energized and the feed valveis opened at block 288. At decision block 310, a determination is madeas to whether there is a flow. If there is no flow then a flow alarm istriggered at block 314. A flow meter measures the amount of uniform fuelproduct is dispensed, and the gallons of such product is captured, asindicated at block 290 and 292. At blocks 294 and 296, the cumulativetotal and cycle total of uniform fuel product dispensed is recorded. Themeter continues until the appropriate uniform fuel product setpoint isreached at block 312. Once the desired feed amount setpoint is reached,the PLC closes the feed valve and waits the remainder of the one hourperiod for the feed cycle to be restarted, as indicated at block 316.

By programmatically controlling the feed valve, the total solids load ofthe digester is better balanced and the load transients are managedthereby creating a more stable operating environment.

While the present invention has been described with reference to one ormore particular embodiments, those skilled in the art will recognizethat many changes may be made thereto without departing from the spiritand scope of the present invention. Each of these embodiments andobvious variations thereof is contemplated as falling within the spiritand scope of the claimed invention, which is set forth in the followingclaims.

The present invention thus includes a computer program which may behosted on a storage medium and includes instructions which perform theprocesses set forth in the present specification. The storage medium caninclude, but is not limited to, any type of disk including floppy disks,optical disks, CD-ROMs, magneto-optical disks, ROMs, RAMs, EPROMs,EEPROMs, flash memory, magnetic or optical cards, or any type of mediasuitable for storing electronic instructions.

Obviously, many other modifications and variations of the presentinvention are possible in light of the above teachings. The specificembodiments discussed herein are merely illustrative, and are not meantto limit the scope of the present invention in any manner. It istherefore to be understood that within the scope of the disclosedconcept, the invention may be practiced otherwise then as specificallydescribed.

1. An organic waste processing system to produce to produce a slurry forthe production of bio-gas, transportation fuels and chemical products,and a residual solid, comprising: a hopper configured to receive sortedorganic waste having contaminants from one or more sources; a separatorsystem in communication with the hopper and configured to receive thesorted organic waste from the hopper and to remove at least a portion ofthe contaminants in the sorted organic waste, wherein the separatorsystem comprises a primary centrifugal separator; a complimentary liquidtank in communication with the separator system and containingcomplimentary liquids, wherein at least a portion of the complimentaryliquids from the complimentary liquid tank is periodically injected intothe separator system upon request; a wash water liquid tank incommunication with the separator system and containing wash water,wherein at least a portion of the wash water from the wash water tank isperiodically injected into the separator system upon request; a producttank in communication with the separator system and configured toreceive the sorted organic waste from the separator system; a make-upproduct tank in communication with the separator system and configuredto receive the sorted organic waste from the separator system having lowCOD, wherein at least a portion of the organic waste from the make-upproduct tank is periodically injected into the product tank uponrequest; an anaerobic digester system configured to receive the sortedorganic waste from the product tank, wherein the anaerobic digestorsystem comprises a flow meter, a control valve and an anaerobic digesterc, wherein the control valve has an open and close position; and aprogrammable logic controller, wherein the programmable logic controlleris configured to periodically inject organic waste into the anaerobicdigestor tank to enhance anaerobic digestion, wherein the programmablelogic controller is configured to monitor the flow meter and to open anddose the control valve to inject the organic waste into the anaerobicdigester tank.
 2. The system of claim 1, the separator system furthercomprising a secondary centrifugal separator in communication with theprimary centrifugal separator and configured to receive the organicwaste from the primary centrifugal separator and to remove at least aportion of the contaminants in the organic waste.
 3. The system of claim2, further comprising a FOG tank in communication with the separatorsystem and containing FOG, wherein at least a portion of the FOG fromthe FOG tank is periodically injected into the product tank uponrequest.
 4. The system of claim 2, further comprising a phase separatedFOG tank in communication with the separator system and containing phaseseparated FOG, wherein at least a portion of the phase separated FOGfrom the phase separated FOG tank is periodically injected into theproduct tank upon request.
 5. The system of claim 2, the primarycentrifugal separator is configured to remove contaminants greater than15 millimeters from the organic waste.
 6. The system of claim 3, thesecondary centrifugal separator is configured to remove contaminantsgreater than 8 millimeters from the organic waste.
 7. The system ofclaim 2, wherein complimentary liquids comprises at least one selectedfrom the group consisting of grease trap material, decased consumerproducts, off-spec consumer products, and beverage industry industrialprocess waste waters.
 8. The system of claim 2, further comprising asupervisory control and data acquisition interface configured to controlat least a portion of the organic waste processing system remotely overthe internet.
 9. The system of claim 2, wherein the programmable logiccontroller is configured to control at least one selected from the groupconsisting of a pump cycle start, a pump cycle stop, a feed cycle start,a feed cycle stop, a feed cycle reset.
 10. The system of claim 2,wherein the programmable logic controller is configured to close thecontrol valve after a predetermined setpoint is reached.
 11. The systemof claim 2, wherein the programmable logic controller is configured tomonitor at least one selected from the group consisting of a cumulativeamount of the organic waste fed into the anaerobic digestor tank and acurrent cycle amount of the organic waste fed into the anaerobicdigestor tank.
 12. A method for producing a slurry for the production ofbio-gas, transportation fuels and chemical products, and a residualsolid, comprising: receiving, into a hopper, sorted organic waste havingcontaminants from one or more sources; receiving, into a separatorsystem in communication with the hopper, at least a portion of thesorted organic waste from the hopper and removing at least a portion ofthe contaminants in the sorted organic waste, wherein the separatorsystem comprises a primary centrifugal separator; periodicallyinjecting, from a complimentary liquid tank having complimentary liquid,at least a portion of the complimentary liquids into the separatorsystem upon request; periodically injecting, from a wash water liquidtank having wash water, at least a portion of the wash water into theseparator system upon request; receiving, into a product tank incommunication with the separator system, at least a portion of thesorted organic waste from the separator system; receiving, into amake-up product tank in communication with the separator system, atleast a portion of the sorted organic waste from the separator system,wherein the make-up product tank receives organic waste having a lowCOD; periodically injecting, into the product tank, at least a portionof the organic waste having a low COD from the make-up product tank uponrequest; receiving, into a anaerobic digestor system, the sorted organicwaste from the product tank, wherein the anaerobic digestor systemcomprises a flow meter, a control valve and an anaerobic digestor tank,wherein the control valve has an open and close position; anaerobicdigesting the organic waste in the anaerobic digestor tank; andcontrolling the flow of the organic waste into the anaerobic digestortank to enhance anaerobic digestion, wherein the flow is controlled by aprogrammable logic controller that is configured to periodically injectorganic waste into the anaerobic digestor tank, wherein the programmablelogic controller is configured to monitor the flow meter and to open andclose the control valve to inject the organic waste into the anaerobicdigestor tank.
 13. The method of claim 12, wherein the separator systemfurther includes a secondary centrifugal separator in communication withthe primary centrifugal separator, and wherein the system furthercomprises and configured to receive the organic waste from the primarycentrifugal separator and to remove at least a portion of thecontaminants in the organic waste.
 14. The method of claim 12, furthercomprising periodically injecting, from a FOG tank having FOG, at leasta portion of the FOG into the product tank upon request.
 15. The methodof claim 12, further comprising periodically injecting, from a phaseseparated FOG tank having phase separated FOG, at least a portion of thephase separated FOG into the product tank upon request.